The present invention relates to a porous structure comprising fungal cell walls having good absorbing, fluid transporting, as well as macro molecular and micro organism binding properties, methods for producing the same as well as its use i wound and hygienic products, such as products for wound treatment and personal hygiene as well as filtering aid.
A material that absorbs large amounts of liquid consists traditionally of cross linked synthetic polymers so called super absorbents (SAP), whereby super absorbents in commercial use within the hygiene product industry consist of cross linked polyacrylates. Today the super absorbents will be used i napkins, sanitary towels and the like. The problem using synthetic absorbents is that they are not biologically degradable. Thus one has lately striven for a good and biologically degradable absorbent.
Super absorbing materials have normally, due to both chemical/physical properties and physical shape a very restricted ability to spread a fluid. In order to increase the spreading ability, carrier fibres are added today, such as cellulose. If there was an absorbent which was self-spreading with regard to the fluid one would be able to exclude or reduce this additive.
Another field of use of the absorbents is in wound treatment products such as compresses and wound bandages. Such products should, besides binding fluid, have properties that prevents bacteria and other micro organisms from growing, propagating and spreading. Bacteria influence the healing coarse of wounds and can be spread to surrounding tissue. It is thus a desire that bandage material can absorb bacteria and bind optional degraded products in an effective manner simultaneously as the liquid of the wound is absorbed.
Fungi comprising chitin and chitosane have turned out to have certain wound healing ability and have thus been used in wound treatment products. A wound treatment bandage is described in U.S. Pat. No. 4,960,413, comprising a bunch of fibres derived from micro fungi having been treated with an alkaline solution only in order to obtain chitin and chitosane. They use hyphae of mould fungi which hyphae are threads which is the mould fungi, and thus utilize only the walls of the cells. This material is directed to unspecific wound healing and does not utilize biological super absorption.
In J. of Biomed. Material Res., vol 28, 1994, pp. 463-469, one has investigated different cultures of fungi as a raw material for chitin and chitosane. Hereby one has treated the material using sodium hydroxide and acetic acid in order to produce as pure a chitin/chitosane material as possible. However, there is no information given that the material obtained could have a good absorbing ability.
Swedish patent having No. 465,678 relates to a fungal cell wall material comprising hexose amine and chitin and chitosane. In the patent it is shown that the material can be used for recovering or eliminating products being negatively charged from water based media. The fungal material can be used e.g., as a selective flocculant and/or ion exchanger for chemical compounds and polymers, e.g., proteins, such as enzymes from aqueous liquids. This material has a compact structure having a restricted liquid absorbing ability.
The object of the present invention is to create a porous structure which absorbs fluid and which, moreover, fulfils above indicated desired features of such a material.